Abstract: An endoprosthetic bone joint device, particularly suitable for a finger or toe joint, comprises two cups and a ball or other roller freely located in and between the cups in articulatory engagement. Normally the cups do not wholly encompass the ball, and so allow flexion-extension simulating articulation limited by mutual abutment of relevant portions of the cup rims. For this purpose, at least one of the cup rims is contoured from planar form to provide two mutually-inclined, diametrically-opposed stop surfaces. Various requirements for abduction-adduction function simulation can also be accommodated by curved profiling of said one cup rim between its stop surfaces.

Abstract: An endoprosthetic bone joint device for the talo-navicular joint comprises two generally similar components each of disc form with one face curved to define a bearing surface and the other face provided with an elongated, relatively shallow, relieved configuration extending across the latter face, the components differing by having complementary bearing surfaces of respectively convex and concave shape. The bearing surface shapes are suitably spherical and the relieved configurations provided by a longitudinally tapered rib with undercut side faces. In use, the joint is approached from above, the bones formed with downward slots to receive the component ribs by translation, and the components with convex and concave bearing surfaces respectively cemented to the talus and navicular.